xref: /openbmc/linux/net/caif/cfpkt_skbuff.c (revision df2634f43f5106947f3735a0b61a6527a4b278cd) 
1 /*
2  * Copyright (C) ST-Ericsson AB 2010
3  * Author:	Sjur Brendeland/sjur.brandeland@stericsson.com
4  * License terms: GNU General Public License (GPL) version 2
5  */
6 
7 #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
8 
9 #include <linux/string.h>
10 #include <linux/skbuff.h>
11 #include <linux/hardirq.h>
12 #include <net/caif/cfpkt.h>
13 
14 #define PKT_PREFIX  48
15 #define PKT_POSTFIX 2
16 #define PKT_LEN_WHEN_EXTENDING 128
17 #define PKT_ERROR(pkt, errmsg)		   \
18 do {					   \
19 	cfpkt_priv(pkt)->erronous = true;  \
20 	skb_reset_tail_pointer(&pkt->skb); \
21 	pr_warn(errmsg);		   \
22 } while (0)
23 
24 struct cfpktq {
25 	struct sk_buff_head head;
26 	atomic_t count;
27 	/* Lock protects count updates */
28 	spinlock_t lock;
29 };
30 
31 /*
32  * net/caif/ is generic and does not
33  * understand SKB, so we do this typecast
34  */
35 struct cfpkt {
36 	struct sk_buff skb;
37 };
38 
39 /* Private data inside SKB */
40 struct cfpkt_priv_data {
41 	struct dev_info dev_info;
42 	bool erronous;
43 };
44 
45 inline struct cfpkt_priv_data *cfpkt_priv(struct cfpkt *pkt)
46 {
47 	return (struct cfpkt_priv_data *) pkt->skb.cb;
48 }
49 
50 inline bool is_erronous(struct cfpkt *pkt)
51 {
52 	return cfpkt_priv(pkt)->erronous;
53 }
54 
55 inline struct sk_buff *pkt_to_skb(struct cfpkt *pkt)
56 {
57 	return &pkt->skb;
58 }
59 
60 inline struct cfpkt *skb_to_pkt(struct sk_buff *skb)
61 {
62 	return (struct cfpkt *) skb;
63 }
64 
65 
66 struct cfpkt *cfpkt_fromnative(enum caif_direction dir, void *nativepkt)
67 {
68 	struct cfpkt *pkt = skb_to_pkt(nativepkt);
69 	cfpkt_priv(pkt)->erronous = false;
70 	return pkt;
71 }
72 EXPORT_SYMBOL(cfpkt_fromnative);
73 
74 void *cfpkt_tonative(struct cfpkt *pkt)
75 {
76 	return (void *) pkt;
77 }
78 EXPORT_SYMBOL(cfpkt_tonative);
79 
80 static struct cfpkt *cfpkt_create_pfx(u16 len, u16 pfx)
81 {
82 	struct sk_buff *skb;
83 
84 	if (likely(in_interrupt()))
85 		skb = alloc_skb(len + pfx, GFP_ATOMIC);
86 	else
87 		skb = alloc_skb(len + pfx, GFP_KERNEL);
88 
89 	if (unlikely(skb == NULL))
90 		return NULL;
91 
92 	skb_reserve(skb, pfx);
93 	return skb_to_pkt(skb);
94 }
95 
96 inline struct cfpkt *cfpkt_create(u16 len)
97 {
98 	return cfpkt_create_pfx(len + PKT_POSTFIX, PKT_PREFIX);
99 }
100 EXPORT_SYMBOL(cfpkt_create);
101 
102 void cfpkt_destroy(struct cfpkt *pkt)
103 {
104 	struct sk_buff *skb = pkt_to_skb(pkt);
105 	kfree_skb(skb);
106 }
107 EXPORT_SYMBOL(cfpkt_destroy);
108 
109 inline bool cfpkt_more(struct cfpkt *pkt)
110 {
111 	struct sk_buff *skb = pkt_to_skb(pkt);
112 	return skb->len > 0;
113 }
114 EXPORT_SYMBOL(cfpkt_more);
115 
116 int cfpkt_peek_head(struct cfpkt *pkt, void *data, u16 len)
117 {
118 	struct sk_buff *skb = pkt_to_skb(pkt);
119 	if (skb_headlen(skb) >= len) {
120 		memcpy(data, skb->data, len);
121 		return 0;
122 	}
123 	return !cfpkt_extr_head(pkt, data, len) &&
124 	    !cfpkt_add_head(pkt, data, len);
125 }
126 EXPORT_SYMBOL(cfpkt_peek_head);
127 
128 int cfpkt_extr_head(struct cfpkt *pkt, void *data, u16 len)
129 {
130 	struct sk_buff *skb = pkt_to_skb(pkt);
131 	u8 *from;
132 	if (unlikely(is_erronous(pkt)))
133 		return -EPROTO;
134 
135 	if (unlikely(len > skb->len)) {
136 		PKT_ERROR(pkt, "read beyond end of packet\n");
137 		return -EPROTO;
138 	}
139 
140 	if (unlikely(len > skb_headlen(skb))) {
141 		if (unlikely(skb_linearize(skb) != 0)) {
142 			PKT_ERROR(pkt, "linearize failed\n");
143 			return -EPROTO;
144 		}
145 	}
146 	from = skb_pull(skb, len);
147 	from -= len;
148 	memcpy(data, from, len);
149 	return 0;
150 }
151 EXPORT_SYMBOL(cfpkt_extr_head);
152 
153 int cfpkt_extr_trail(struct cfpkt *pkt, void *dta, u16 len)
154 {
155 	struct sk_buff *skb = pkt_to_skb(pkt);
156 	u8 *data = dta;
157 	u8 *from;
158 	if (unlikely(is_erronous(pkt)))
159 		return -EPROTO;
160 
161 	if (unlikely(skb_linearize(skb) != 0)) {
162 		PKT_ERROR(pkt, "linearize failed\n");
163 		return -EPROTO;
164 	}
165 	if (unlikely(skb->data + len > skb_tail_pointer(skb))) {
166 		PKT_ERROR(pkt, "read beyond end of packet\n");
167 		return -EPROTO;
168 	}
169 	from = skb_tail_pointer(skb) - len;
170 	skb_trim(skb, skb->len - len);
171 	memcpy(data, from, len);
172 	return 0;
173 }
174 EXPORT_SYMBOL(cfpkt_extr_trail);
175 
176 int cfpkt_pad_trail(struct cfpkt *pkt, u16 len)
177 {
178 	return cfpkt_add_body(pkt, NULL, len);
179 }
180 EXPORT_SYMBOL(cfpkt_pad_trail);
181 
182 int cfpkt_add_body(struct cfpkt *pkt, const void *data, u16 len)
183 {
184 	struct sk_buff *skb = pkt_to_skb(pkt);
185 	struct sk_buff *lastskb;
186 	u8 *to;
187 	u16 addlen = 0;
188 
189 
190 	if (unlikely(is_erronous(pkt)))
191 		return -EPROTO;
192 
193 	lastskb = skb;
194 
195 	/* Check whether we need to add space at the tail */
196 	if (unlikely(skb_tailroom(skb) < len)) {
197 		if (likely(len < PKT_LEN_WHEN_EXTENDING))
198 			addlen = PKT_LEN_WHEN_EXTENDING;
199 		else
200 			addlen = len;
201 	}
202 
203 	/* Check whether we need to change the SKB before writing to the tail */
204 	if (unlikely((addlen > 0) || skb_cloned(skb) || skb_shared(skb))) {
205 
206 		/* Make sure data is writable */
207 		if (unlikely(skb_cow_data(skb, addlen, &lastskb) < 0)) {
208 			PKT_ERROR(pkt, "cow failed\n");
209 			return -EPROTO;
210 		}
211 		/*
212 		 * Is the SKB non-linear after skb_cow_data()? If so, we are
213 		 * going to add data to the last SKB, so we need to adjust
214 		 * lengths of the top SKB.
215 		 */
216 		if (lastskb != skb) {
217 			pr_warn("Packet is non-linear\n");
218 			skb->len += len;
219 			skb->data_len += len;
220 		}
221 	}
222 
223 	/* All set to put the last SKB and optionally write data there. */
224 	to = skb_put(lastskb, len);
225 	if (likely(data))
226 		memcpy(to, data, len);
227 	return 0;
228 }
229 EXPORT_SYMBOL(cfpkt_add_body);
230 
231 inline int cfpkt_addbdy(struct cfpkt *pkt, u8 data)
232 {
233 	return cfpkt_add_body(pkt, &data, 1);
234 }
235 EXPORT_SYMBOL(cfpkt_addbdy);
236 
237 int cfpkt_add_head(struct cfpkt *pkt, const void *data2, u16 len)
238 {
239 	struct sk_buff *skb = pkt_to_skb(pkt);
240 	struct sk_buff *lastskb;
241 	u8 *to;
242 	const u8 *data = data2;
243 	int ret;
244 	if (unlikely(is_erronous(pkt)))
245 		return -EPROTO;
246 	if (unlikely(skb_headroom(skb) < len)) {
247 		PKT_ERROR(pkt, "no headroom\n");
248 		return -EPROTO;
249 	}
250 
251 	/* Make sure data is writable */
252 	ret = skb_cow_data(skb, 0, &lastskb);
253 	if (unlikely(ret < 0)) {
254 		PKT_ERROR(pkt, "cow failed\n");
255 		return ret;
256 	}
257 
258 	to = skb_push(skb, len);
259 	memcpy(to, data, len);
260 	return 0;
261 }
262 EXPORT_SYMBOL(cfpkt_add_head);
263 
264 inline int cfpkt_add_trail(struct cfpkt *pkt, const void *data, u16 len)
265 {
266 	return cfpkt_add_body(pkt, data, len);
267 }
268 EXPORT_SYMBOL(cfpkt_add_trail);
269 
270 inline u16 cfpkt_getlen(struct cfpkt *pkt)
271 {
272 	struct sk_buff *skb = pkt_to_skb(pkt);
273 	return skb->len;
274 }
275 EXPORT_SYMBOL(cfpkt_getlen);
276 
277 inline u16 cfpkt_iterate(struct cfpkt *pkt,
278 			    u16 (*iter_func)(u16, void *, u16),
279 			    u16 data)
280 {
281 	/*
282 	 * Don't care about the performance hit of linearizing,
283 	 * Checksum should not be used on high-speed interfaces anyway.
284 	 */
285 	if (unlikely(is_erronous(pkt)))
286 		return -EPROTO;
287 	if (unlikely(skb_linearize(&pkt->skb) != 0)) {
288 		PKT_ERROR(pkt, "linearize failed\n");
289 		return -EPROTO;
290 	}
291 	return iter_func(data, pkt->skb.data, cfpkt_getlen(pkt));
292 }
293 EXPORT_SYMBOL(cfpkt_iterate);
294 
295 int cfpkt_setlen(struct cfpkt *pkt, u16 len)
296 {
297 	struct sk_buff *skb = pkt_to_skb(pkt);
298 
299 
300 	if (unlikely(is_erronous(pkt)))
301 		return -EPROTO;
302 
303 	if (likely(len <= skb->len)) {
304 		if (unlikely(skb->data_len))
305 			___pskb_trim(skb, len);
306 		else
307 			skb_trim(skb, len);
308 
309 			return cfpkt_getlen(pkt);
310 	}
311 
312 	/* Need to expand SKB */
313 	if (unlikely(!cfpkt_pad_trail(pkt, len - skb->len)))
314 		PKT_ERROR(pkt, "skb_pad_trail failed\n");
315 
316 	return cfpkt_getlen(pkt);
317 }
318 EXPORT_SYMBOL(cfpkt_setlen);
319 
320 struct cfpkt *cfpkt_create_uplink(const unsigned char *data, unsigned int len)
321 {
322 	struct cfpkt *pkt = cfpkt_create_pfx(len + PKT_POSTFIX, PKT_PREFIX);
323 	if (!pkt)
324 		return NULL;
325 	if (unlikely(data != NULL))
326 		cfpkt_add_body(pkt, data, len);
327 	return pkt;
328 }
329 EXPORT_SYMBOL(cfpkt_create_uplink);
330 
331 struct cfpkt *cfpkt_append(struct cfpkt *dstpkt,
332 			     struct cfpkt *addpkt,
333 			     u16 expectlen)
334 {
335 	struct sk_buff *dst = pkt_to_skb(dstpkt);
336 	struct sk_buff *add = pkt_to_skb(addpkt);
337 	u16 addlen = skb_headlen(add);
338 	u16 neededtailspace;
339 	struct sk_buff *tmp;
340 	u16 dstlen;
341 	u16 createlen;
342 	if (unlikely(is_erronous(dstpkt) || is_erronous(addpkt))) {
343 		return dstpkt;
344 	}
345 	if (expectlen > addlen)
346 		neededtailspace = expectlen;
347 	else
348 		neededtailspace = addlen;
349 
350 	if (dst->tail + neededtailspace > dst->end) {
351 		/* Create a dumplicate of 'dst' with more tail space */
352 		struct cfpkt *tmppkt;
353 		dstlen = skb_headlen(dst);
354 		createlen = dstlen + neededtailspace;
355 		tmppkt = cfpkt_create(createlen + PKT_PREFIX + PKT_POSTFIX);
356 		if (tmppkt == NULL)
357 			return NULL;
358 		tmp = pkt_to_skb(tmppkt);
359 		skb_set_tail_pointer(tmp, dstlen);
360 		tmp->len = dstlen;
361 		memcpy(tmp->data, dst->data, dstlen);
362 		cfpkt_destroy(dstpkt);
363 		dst = tmp;
364 	}
365 	memcpy(skb_tail_pointer(dst), add->data, skb_headlen(add));
366 	cfpkt_destroy(addpkt);
367 	dst->tail += addlen;
368 	dst->len += addlen;
369 	return skb_to_pkt(dst);
370 }
371 EXPORT_SYMBOL(cfpkt_append);
372 
373 struct cfpkt *cfpkt_split(struct cfpkt *pkt, u16 pos)
374 {
375 	struct sk_buff *skb2;
376 	struct sk_buff *skb = pkt_to_skb(pkt);
377 	struct cfpkt *tmppkt;
378 	u8 *split = skb->data + pos;
379 	u16 len2nd = skb_tail_pointer(skb) - split;
380 
381 	if (unlikely(is_erronous(pkt)))
382 		return NULL;
383 
384 	if (skb->data + pos > skb_tail_pointer(skb)) {
385 		PKT_ERROR(pkt, "trying to split beyond end of packet\n");
386 		return NULL;
387 	}
388 
389 	/* Create a new packet for the second part of the data */
390 	tmppkt = cfpkt_create_pfx(len2nd + PKT_PREFIX + PKT_POSTFIX,
391 				  PKT_PREFIX);
392 	if (tmppkt == NULL)
393 		return NULL;
394 	skb2 = pkt_to_skb(tmppkt);
395 
396 
397 	if (skb2 == NULL)
398 		return NULL;
399 
400 	/* Reduce the length of the original packet */
401 	skb_set_tail_pointer(skb, pos);
402 	skb->len = pos;
403 
404 	memcpy(skb2->data, split, len2nd);
405 	skb2->tail += len2nd;
406 	skb2->len += len2nd;
407 	return skb_to_pkt(skb2);
408 }
409 EXPORT_SYMBOL(cfpkt_split);
410 
411 char *cfpkt_log_pkt(struct cfpkt *pkt, char *buf, int buflen)
412 {
413 	struct sk_buff *skb = pkt_to_skb(pkt);
414 	char *p = buf;
415 	int i;
416 
417 	/*
418 	 * Sanity check buffer length, it needs to be at least as large as
419 	 * the header info: ~=50+ bytes
420 	 */
421 	if (buflen < 50)
422 		return NULL;
423 
424 	snprintf(buf, buflen, "%s: pkt:%p len:%ld(%ld+%ld) {%ld,%ld} data: [",
425 		is_erronous(pkt) ? "ERRONOUS-SKB" :
426 		 (skb->data_len != 0 ? "COMPLEX-SKB" : "SKB"),
427 		 skb,
428 		 (long) skb->len,
429 		 (long) (skb_tail_pointer(skb) - skb->data),
430 		 (long) skb->data_len,
431 		 (long) (skb->data - skb->head),
432 		 (long) (skb_tail_pointer(skb) - skb->head));
433 	p = buf + strlen(buf);
434 
435 	for (i = 0; i < skb_tail_pointer(skb) - skb->data && i < 300; i++) {
436 		if (p > buf + buflen - 10) {
437 			sprintf(p, "...");
438 			p = buf + strlen(buf);
439 			break;
440 		}
441 		sprintf(p, "%02x,", skb->data[i]);
442 		p = buf + strlen(buf);
443 	}
444 	sprintf(p, "]\n");
445 	return buf;
446 }
447 EXPORT_SYMBOL(cfpkt_log_pkt);
448 
449 int cfpkt_raw_append(struct cfpkt *pkt, void **buf, unsigned int buflen)
450 {
451 	struct sk_buff *skb = pkt_to_skb(pkt);
452 	struct sk_buff *lastskb;
453 
454 	caif_assert(buf != NULL);
455 	if (unlikely(is_erronous(pkt)))
456 		return -EPROTO;
457 	/* Make sure SKB is writable */
458 	if (unlikely(skb_cow_data(skb, 0, &lastskb) < 0)) {
459 		PKT_ERROR(pkt, "skb_cow_data failed\n");
460 		return -EPROTO;
461 	}
462 
463 	if (unlikely(skb_linearize(skb) != 0)) {
464 		PKT_ERROR(pkt, "linearize failed\n");
465 		return -EPROTO;
466 	}
467 
468 	if (unlikely(skb_tailroom(skb) < buflen)) {
469 		PKT_ERROR(pkt, "buffer too short - failed\n");
470 		return -EPROTO;
471 	}
472 
473 	*buf = skb_put(skb, buflen);
474 	return 1;
475 }
476 EXPORT_SYMBOL(cfpkt_raw_append);
477 
478 int cfpkt_raw_extract(struct cfpkt *pkt, void **buf, unsigned int buflen)
479 {
480 	struct sk_buff *skb = pkt_to_skb(pkt);
481 
482 	caif_assert(buf != NULL);
483 	if (unlikely(is_erronous(pkt)))
484 		return -EPROTO;
485 
486 	if (unlikely(buflen > skb->len)) {
487 		PKT_ERROR(pkt, "buflen too large - failed\n");
488 		return -EPROTO;
489 	}
490 
491 	if (unlikely(buflen > skb_headlen(skb))) {
492 		if (unlikely(skb_linearize(skb) != 0)) {
493 			PKT_ERROR(pkt, "linearize failed\n");
494 			return -EPROTO;
495 		}
496 	}
497 
498 	*buf = skb->data;
499 	skb_pull(skb, buflen);
500 
501 	return 1;
502 }
503 EXPORT_SYMBOL(cfpkt_raw_extract);
504 
505 inline bool cfpkt_erroneous(struct cfpkt *pkt)
506 {
507 	return cfpkt_priv(pkt)->erronous;
508 }
509 EXPORT_SYMBOL(cfpkt_erroneous);
510 
511 struct cfpktq *cfpktq_create(void)
512 {
513 	struct cfpktq *q = kmalloc(sizeof(struct cfpktq), GFP_ATOMIC);
514 	if (!q)
515 		return NULL;
516 	skb_queue_head_init(&q->head);
517 	atomic_set(&q->count, 0);
518 	spin_lock_init(&q->lock);
519 	return q;
520 }
521 EXPORT_SYMBOL(cfpktq_create);
522 
523 void cfpkt_queue(struct cfpktq *pktq, struct cfpkt *pkt, unsigned short prio)
524 {
525 	atomic_inc(&pktq->count);
526 	spin_lock(&pktq->lock);
527 	skb_queue_tail(&pktq->head, pkt_to_skb(pkt));
528 	spin_unlock(&pktq->lock);
529 
530 }
531 EXPORT_SYMBOL(cfpkt_queue);
532 
533 struct cfpkt *cfpkt_qpeek(struct cfpktq *pktq)
534 {
535 	struct cfpkt *tmp;
536 	spin_lock(&pktq->lock);
537 	tmp = skb_to_pkt(skb_peek(&pktq->head));
538 	spin_unlock(&pktq->lock);
539 	return tmp;
540 }
541 EXPORT_SYMBOL(cfpkt_qpeek);
542 
543 struct cfpkt *cfpkt_dequeue(struct cfpktq *pktq)
544 {
545 	struct cfpkt *pkt;
546 	spin_lock(&pktq->lock);
547 	pkt = skb_to_pkt(skb_dequeue(&pktq->head));
548 	if (pkt) {
549 		atomic_dec(&pktq->count);
550 		caif_assert(atomic_read(&pktq->count) >= 0);
551 	}
552 	spin_unlock(&pktq->lock);
553 	return pkt;
554 }
555 EXPORT_SYMBOL(cfpkt_dequeue);
556 
557 int cfpkt_qcount(struct cfpktq *pktq)
558 {
559 	return atomic_read(&pktq->count);
560 }
561 EXPORT_SYMBOL(cfpkt_qcount);
562 
563 struct cfpkt *cfpkt_clone_release(struct cfpkt *pkt)
564 {
565 	struct cfpkt *clone;
566 	clone  = skb_to_pkt(skb_clone(pkt_to_skb(pkt), GFP_ATOMIC));
567 	/* Free original packet. */
568 	cfpkt_destroy(pkt);
569 	if (!clone)
570 		return NULL;
571 	return clone;
572 }
573 EXPORT_SYMBOL(cfpkt_clone_release);
574 
575 struct caif_payload_info *cfpkt_info(struct cfpkt *pkt)
576 {
577 	return (struct caif_payload_info *)&pkt_to_skb(pkt)->cb;
578 }
579 EXPORT_SYMBOL(cfpkt_info);
580